محمدرضا کماندار

The information of the shearing properties of buxus stalk plays an important role in the design and fabrication of buxus pruning machine. A series of laboratory tests were conducted to measure the shear force, shear consumption energy and shear strength of stem internodes of buxus stalk under impact cutting at four loading rates (1, 2, 3 and 4 m s-1), three internodes (fifth, tenth and fifteenth), and moisture content level 72% w.b. In this test, the stalk specimens were served in impact cutting process by using a special cutting test apparatus that was designed, fabricated, and calibrated. To define the impact cutting force of buxus stem, the apparatus was attached with beam type load cell and shear blade. The variance analysis of the data results showed that the effect of loading rate and internode position on shear consumption energy and shear strength were significant (P<0.01). Also, the interaction of loading rate and internode position effect on mentioned parameters were significant (P<0.01). The results showed shear strength and shear consumption energy decreased with an increase in loading rate and upward from fifteenth to fifth internode position. The minimum and maximum values of shear consumption energy were obtained as 3.19 J at fifth internode and loading rate: 4 m s-1 and 19.6 J at fifteenth internode and loading rate: 1 m s-1, respectively. The minimum and maximum values of shear strength were obtained as 0.06 MPa at fifth internode and loading rate: 4 m s-1 and 1.55 MPa at fifteenth internode and loading rate: 1 m s-1, respectively. Based on the statistical analysis, the average values of shear strength and shear consumption energy were obtained as 13.8 J from 3.19 to 19.60 J, and 0.66 MPa from o.71 to 1.03 MPa, respectively.